1. Field of the Invention
The invention relates to a polymeric composition having good hardness, stiffness and tear strength and good resistance to flex cracking, solvent attack and abrasion. More particularly, the invention relates to a polymeric composition containing a mixture of two radial monoalkenyl arene conjugated diene block copolymers and a linear low density polyethylene along with various other components.
2. Description of the Prior Art
The use of certain block copolymers and their compounds in a number of end-uses and especially footwear, is rapidly expanding. For example, in the footwear industry, certain block copolymer compounds are being used in large volume in the manufacture of a wide variety of shoes including canvas shoes, sport shoes, and dress shoes. The block copolymers may be utilized for this purpose for soling, foxing, innersoles and the like. These compositions are disclosed in Hendricks et al, U.S. Pat. Re. No. 28,236. In general, these shoe component compositions usually comprise a mixture of block copolymer, extending oil, polystyrene and possibly a filler.
For the most part, these block copolymer compositions have proven to be particularly advantageous in many respects, including flexibility, processability, lack of vulcanization requirement and wet slip. However, in certain respects, shortcomings have been noted. For example, commercial compounds should be free from delamination and free from elephant hide. For some important commercial applications, it is also important that the shoe soles also possess solvent resistance and oil resistance. Improved footwear compositions have been made, such as those compositions disclosed in U.S. Pat. Nos. 4,216,131 and 4,216,132. However, the prior art compositions still did not possess sufficient solvent resistance. U.S. Pat. No. 4,216,131 disclosed a composition containing ethylene-vinyl acetate (EVA) and low density polyethylene. U.S. Pat. No. 4,216,132 disclosed a composition containing high density polyethylene and U.S. Pat. No. 4,377,658 disclosed a composition containing ethylene vinyl acetate copolymer and high density polyethylene. All of these showed improved properties. U.S. application Ser. No. 524,835 disclosed a composition containing a combination of EVA and linear low density polyethylene (LLDPE). It has now been found that a composition containing a mixture of radial block copolymers and linear low density polyethylene (LLDPE) alone exhibits comparable properties at some cost saving since LLDPE is less expensive than analogs used previously.